Ancient and ongoing hybridization in the Oreochromis cichlid fishes
Ancient and ongoing hybridization in the Oreochromis cichlid fishes
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DOI：
10.1101/2023.05.19.541459
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发表时间：
2023-09
期刊：
影响因子：
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通讯作者：
A. Ciezarek;Tarang K. Mehta;Angela Man;Antonia G P Ford;G. D. Kavembe;N. Kasozi;B. Ngatunga;A. Shec
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文献类型：
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作者：
A. Ciezarek;Tarang K. Mehta;Angela Man;Antonia G P Ford;G. D. Kavembe;N. Kasozi;B. Ngatunga;A. Shec
当杂交谱系面临生态机遇时，杂交可以通过产生独特的遗传组合来实现适应性多样化。相反，与外来物种杂交可能会导致同质化和丢失与当地适应相关的重要遗传物质，从而损害本地生物多样性。本文研究了罗非鱼属（Oreochromis，罗非鱼）的古代和现代杂交。罗非鱼属是全球最重要的水产养殖鱼类之一。我们对来自23种罗非鱼的575个个体进行了全基因组重测序，重点研究了坦桑尼亚，这是罗非鱼多样性的天然热点，也是一个以前报道过自然环境中外来物种和本地物种杂交的国家。我们重建了该属的第一个基因组尺度的系统发育，并揭示了在Oreochromis系统发育中普遍存在的古代基因流。这种渗入并没有像在其他慈鲷谱系中看到的那样导致大规模的适应性辐射。我们在野外发现了多个本地物种和引进物种杂交的案例，这与在水产养殖改进和捕捞渔业放养中使用非本地物种有关。我们的研究表明，古代杂交如何促进现代罗非鱼的多样性，但现在对野生种群的遗传完整性和全球罗非鱼养殖业的长期前景构成威胁。
Hybridization may enable adaptive diversification by generating unique genetic combinations when hybrid lineages are faced with ecological opportunity. Conversely, hybridization with exotic species may be detrimental to native biodiversity, by leading to homogenisation and the loss of important genetic material associated with local adaptation. Here we studied both ancient and contemporary hybridization in cichlid fishes of the genus Oreochromis (tilapia), which are among the most important fish for global aquaculture. We use whole genome resequencing of 575 individuals from 23 species, focussing on Tanzania, a natural hotspot of tilapia diversity, and a country where hybridization between exotic and native species in the natural environment has been previously reported. We reconstruct the first genome-scale phylogeny of the genus and reveal prevalent ancient gene flow across the Oreochromis phylogeny. This introgression has not led to large-scale adaptive radiation as seen in other cichlid lineages. We identify multiple cases of contemporary hybridization between native and introduced species in the wild, linked to the use of non-native species in aquaculture improvement and stocking for capture fisheries. Our study shows how ancient hybridization contributed to modern tilapia diversity, but is now a threat to both the genetic integrity of wild populations and the long-term prospects of the global tilapia aquaculture industry.